fade-in

US: (fād′in′)

WordReference Random House Unabridged Dictionary of American English © 2025

fade-in  (fād′in′), n. 

1. Show Business [Motion Pictures, Television.] a gradual increase in the visibility of a scene.
2. Show Business, Sound Reproduction [Broadcasting, Recording.] a gradual increase in the volume of sound, esp. of recorded or broadcast music, dialogue, or the like, usually starting from complete inaudibility.

• noun, nominal use of verb, verbal phrase fade in 1915–20

Collins Concise English Dictionary © HarperCollins Publishers::

fade-in noun

1. an optical effect in which a shot appears gradually out of darkness

verb
Also: fade up to increase or cause to increase gradually, as vision or sound in a film or broadcast